9 is the blank.
(a+b)^2 = a^2 + 2ab + b^2
a = x
b = 3
(x+3)^2 = x^2 + 6x + 9
Answer:
A
Step-by-step explanation:
Im not sure if its correct tho dont quote me on it ;(
Isolate the variable by dividing each side by factors that don't contain the variable.